Narrowband filtering structure and high-order mode damping cavity

Abstract

The invention discloses a narrowband filtering structure and a high-order mode damping cavity, the narrowband filtering structure comprises a first cavity, the first cavity is provided with an annular cavity penetrating through two opposite surfaces of the cavity, and the inner surface of the annular cavity is provided with an annular coupling groove coaxial with the annular cavity; the insulating ring is coaxial with the annular coupling groove; and the metal ring is arranged on the insulating ring in a sleeving manner and is coaxial with the insulating ring, and the metal ring is arranged in the annular coupling groove so as to form an RLC equivalent circuit structure. According to the technical scheme, due to the fact that the narrow-band filtering structure is equivalent to the RLC equivalent circuit structure, the change rate of a magnetic field near a wave node is reduced, electromagnetic field leakage in the working mode is effectively reduced, and then the working stability of the high-order mode damping cavity under the high gradient is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of particle accelerators, and particularly to a narrowband filtering structure and a higher-order mode damping cavity. Background Art

[0002] In a synchrotron radiation light source, it is necessary to supplement the energy loss caused by the synchrotron radiation light source and insertion devices, etc. to the beam through a particle acceleration cavity. At the same time, the particle acceleration cavity needs to sufficiently suppress the higher-order modes to reduce the multi-bunch coupling instability and improve the beam quality.

[0003] In the prior art, the particle acceleration cavity uses TM020 as the acceleration mode, which increases the volume of the cavity, reduces the surface power density, and improves the cavity pressure bearing capacity (generally greater than 0.8 MV / cell). However, the high-gradient operation stability of the higher-order mode damping cavity depends on the accuracy of the coupling slot position and the wave node position on the higher-order mode damping cavity. Due to the coupling slot position offset caused by processing, installation, thermal deformation, and mechanical stress, etc., and the wave node offset caused by tuners, couplers, etc., serious electromagnetic field leakage will occur. The leaked electromagnetic field energy will be completely absorbed by the damper, and the heat load that the damper can bear is limited, thereby restricting the high-gradient stable operation of the higher-order mode damping cavity.

[0004] Therefore, the prior art still needs to be improved and developed. Summary of the Invention

[0005] In view of the above deficiencies of the prior art, the purpose of the present invention is to provide a narrowband filtering structure and a higher-order mode damping cavity to solve the problem in the prior art that due to the coupling slot position offset caused by processing, installation, thermal deformation, and mechanical stress, etc., and the wave node offset caused by tuners, couplers, etc., serious electromagnetic field leakage will occur. The leaked electromagnetic field energy will be completely absorbed by the damper, and the heat load that the damper can bear is limited, thereby restricting the high-gradient stable operation of the higher-order mode damping cavity.

[0006] The technical solution adopted by the present invention to solve its technical problems is: to provide a narrowband filtering structure, including:

[0007] A first cavity, the first cavity is provided with an annular chamber penetrating through two opposite surfaces of the first cavity, and an annular coupling slot coaxial with the annular chamber is provided on the inner surface of the annular chamber;

[0008] An insulating ring, coaxially arranged with the annular coupling slot;

[0009] A metal ring, sleeved on the insulating ring and coaxially arranged with the insulating ring, the metal ring is arranged in the annular coupling slot to form an RLC equivalent circuit structure.

[0010] Further setting of the present invention: One end of the cavity is folded back circumferentially.

[0011] Further setting of the present invention: One end of the cavity is folded outwards circumferentially; or, one end of the cavity is folded inwards circumferentially.

[0012] Further setting of the present invention: The first cavity is a cylindrical cavity, and a circular ring chamber penetrating the upper surface and the lower surface of the first cavity is provided on the first cavity, and the circular ring chamber is the annular chamber.

[0013] Further setting of the present invention: The metal ring is a circular ring, and the insulating ring is a circular ring.

[0014] Further setting of the present invention: The metal ring is a copper ring or a stainless steel ring.

[0015] Further setting of the present invention: The insulating ring is a ceramic ring.

[0016] The present invention also provides a high-order mode damping cavity, including: the narrowband filtering structure as described above.

[0017] Further setting of the present invention: The high-order mode damping cavity further includes:

[0018] A second cavity, the second cavity is a cylindrical cavity, the narrowband filtering structures are respectively arranged at both ends of the second cavity, one end of the first cavity is connected to the second cavity, the other end of the first cavity extends axially away from the second cavity, and the annular chamber is coaxially arranged with the second cavity.

[0019] Further setting of the present invention: A coupler, a plurality of symmetrically distributed tuners, a damper, a plurality of signal extraction ports and a vacuum pumping port are arranged on the side wall of the second cavity; a damper for absorbing waves is arranged at the other end of each first cavity.

[0020] The beneficial effects of the present invention:

[0021] The present invention discloses a narrowband filtering structure and a high-order mode damping cavity. The narrowband filtering structure includes: a cavity, the cavity is provided with an annular chamber penetrating through two opposite surfaces of the first cavity, and an annular coupling groove coaxial with the annular chamber is provided on the inner surface of the annular chamber; an insulating ring, coaxially arranged with the annular coupling groove; a metal ring, sleeved on the insulating ring and coaxially arranged with the insulating ring, and the metal ring is arranged in the annular coupling groove to form an RLC equivalent circuit structure. In the technical solution of the present invention, since the narrowband filtering structure is equivalent to an RLC equivalent circuit structure, the rate of change of the magnetic field near the wave node is reduced, the electromagnetic field leakage in the working mode is effectively reduced, and the stability of the high-order mode damping cavity working at a high gradient is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0023] Figure 1 It is a structural diagram of the narrowband filtering structure of the present invention.

[0024] Figure 2 It is an exploded view of the narrowband filtering structure in an embodiment of the present invention.

[0025] Figure 3 It is a sectional view of the narrowband filtering structure in an embodiment of the present invention.

[0026] Figure 4 It is a partial enlarged view of the sectional view of the narrowband filtering structure in an embodiment of the present invention.

[0027] Figure 5 It is a sectional view of the first cavity in an embodiment of the present invention.

[0028] Figure 6 It is a structural diagram of the RLC circuit equivalent to the narrowband filtering structure.

[0029] Figure 7 It is a position offset curve graph of the coupling groove of the high-order mode damping cavity when the electromagnetic field leakage rate is 2%.

[0030] Figure 8 It is a relationship graph of transmission efficiency, frequency and quality factor.

[0031] Figure 9 It is a curve graph when the resonance point acts on 1.5 GHz.

[0032] Figure 10 This is the structural diagram of the high-order mode damping cavity of the present invention.

[0033] Marks in the attached drawings: 101, narrowband filtering structure; 1011, first cavity; 1012, insulating ring; 1013, metal ring; 1014, annular chamber; 1015, annular coupling slot; 10, high-order mode damping cavity; 102, second cavity; 103, coupler; 104, tuner; 105, damper; 106, signal extraction port; 107, vacuum pumping port. Specific embodiments

[0034] For a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the attached drawings. In the following description, it should be understood that the orientation or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are based on the orientation or positional relationships shown in the attached drawings, and are constructed and operated in a specific orientation, only for the convenience of describing the present technical solution, rather than indicating that the indicated devices or elements must have a specific orientation, so it should not be construed as a limitation to the present invention.

[0035] Traditional normal-temperature particle acceleration cavities use the TM010 mode as the acceleration mode, and usually utilize the high-pass filtering characteristics of the waveguide structure to effectively suppress high-order modes and protect the working mode (TM010 mode). Taking a 1500 MHz normal-temperature damping cavity as an example, the TM010 mode damping cavity generally has an acceleration cavity pressure less than 0.15 MV / cell, and it is necessary to increase the number of cavities to meet the cavity pressure requirements. However, as the number of cavities increases, the requirements for high-order mode suppression also increase.

[0036] Compared with the TM010 mode damping cavity, the TM020 mode damping cavity uses the TM020 mode as the acceleration mode, which increases the volume of the cavity, reduces the surface power density, and improves the cavity pressure bearing capacity (generally greater than 0.3 MV / cell). At the same time, when using the TM020 mode as the acceleration mode, its characteristic impedance (R / Q) is reduced by half. When applied to a harmonic cavity, it can effectively reduce the periodic bunch coupling instability to improve the stretching bunch efficiency and effectively increase the beam lifetime. In addition, a more prominent feature of the TM020 mode damping cavity is its unique electromagnetic field distribution, which can achieve effective damping of high-order modes and a compact structure design.

[0037] However, the high-frequency performance and high-gradient operation stability of the high-order mode damping cavity adopting the TM020 mode strongly depend on the coupling slot position of the high-order mode damping cavity and the position accuracy of the wave nodes. The offset of the position will cause serious electromagnetic field leakage, and all of it needs to be borne by the damper. Due to processing, installation, thermal stress, mechanical stress, etc., the position of the coupling slot will be offset. Similarly, the introduction of couplers, tuners, etc. will disturb the electromagnetic field distribution, and then cause the position of the wave nodes to shift, resulting in serious electromagnetic field leakage. The leaked electromagnetic field energy will be completely absorbed by the damper, and the heat load that the damper can bear is limited, thus restricting the high-gradient stable operation of the high-order mode damping cavity.

[0038] Aiming at the problems existing in the prior art, the present invention provides a narrowband filtering structure 101, which can be applied to the high-order mode damping cavity 10 adopting the TM020 mode. As Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 shown, the narrowband filtering structure 101 may include a first cavity 1011, an insulating ring 1012 and a metal ring 1013; wherein, the first cavity 1011 is provided with an annular chamber 1014 penetrating through two opposite surfaces of the cavity, and an annular coupling slot 1015 coaxial with the annular chamber is provided on the inner surface of the annular chamber 1014; the insulating ring 1012 is coaxial with the annular coupling slot 1015; the metal ring 1013 is sleeved on the insulating ring 1012 and is coaxial with the insulating ring 1012, and the metal ring 1013 is arranged in the annular coupling slot 1015 to form an RLC equivalent circuit structure (the insulating ring 1012, the metal ring 1013, the annular coupling slot 1015 and the first cavity 1011 constitute an RLC equivalent circuit structure), Figure 6 The RLC circuit structure is the circuit structure equivalent to the narrowband filtering structure 101.

[0039] Specifically, when the first cavity 1011 is set, it can be set as a cylindrical cavity, and a circular annular chamber 1014 penetrating through the upper surface and the lower surface of the cylindrical cavity is provided on the cylindrical cavity, and the circular annular chamber 1014 is the annular chamber 1014.

[0040] An annular coupling slot 1015 is provided on the inner surface of the circular annular chamber 1014, and the annular coupling slot 1015 is coaxial with the circular annular chamber 1014. Among them, the circular annular chamber 1014 and the annular coupling slot 1015 can be integrally formed, that is, during the process of machining the circular annular chamber 1014, the annular coupling slot 1015 is formed on the inner surface of the circular annular chamber 1014. When the annular coupling slot 1015 is opened, the opening position of the annular coupling slot 1015 needs to consider the heat loss, and ensure that the opening position of the annular coupling slot 1015 minimizes the heat loss borne by the narrowband filtering structure.

[0041] Further, as Figure 2 shown, when the annular chamber 1014 is a circular annular chamber 1014, the metal ring 1013 is set as a circular ring, and the circular ring is coaxially arranged with the annular coupling groove 1015. Correspondingly, the insulating ring 1012 is also set as a circular ring, and when the metal ring 1013 is sleeved on the insulating ring 1012, the insulating ring 1012 and the metal ring 1013 are coaxially arranged, that is to say, the insulating ring 1012 is also coaxially arranged with the annular coupling groove 1015.

[0042] In this embodiment, the RLC equivalent circuit structure reduces the magnetic field change rate near the wave node, alleviates the electromagnetic field leakage caused by the offset of the coupling groove and the wave node position of the high-order mode damping cavity 10, and further improves the stability of the high-order mode damping cavity 10 when operating at a high gradient. As Figure 6 shown, it is the RLC circuit structure equivalent to the narrowband filtering structure 101, wherein the function of the insulating ring 1012 is to increase the dielectric constant to improve the capacitance. It can be obtained from the simulation data that as Figure 7 shown, when the electromagnetic field leakage rate is 2%, the allowable offset amount of the coupling groove position of the high-order mode damping cavity 10 increases from ±0.12 mm to ±0.9 mm.

[0043] In some embodiments, as Figure 1 , Figure 2 , Figure 3 and Figure 5 shown, one end of the first cavity 1011 can be folded back circumferentially.

[0044] Specifically, when the narrowband filtering structure 101 is applied, one end of the first cavity 1011 can be folded back circumferentially. When folding back, one end of the first cavity 1011 can be folded back by 90°, so that one end of the first cavity 1011 is substantially in a disc structure.

[0045] Of course, one end of the first cavity 1011 can also be folded back at other angles, for example, folded back at angles such as 88°, 85°, 70°, 65°, 60°, 55°, etc. Those skilled in the art can determine the folding-back angle according to the actual situation, and no further limitation is made here.

[0046] In this embodiment, the folding-back design of the first cavity 1011 can reduce the axial occupied area and reduce the machining cost (if the first cavity 1011 is too long, it will increase the machining cost).

[0047] Further, as Figure 1 , Figure 2As shown, one end of the first cavity 1011 can be folded outward circumferentially or inward circumferentially, that is, one end of the first cavity 1011 can be folded inward circumferentially, and one end of the first cavity 1011 can also be folded outward circumferentially. Those skilled in the art can determine whether the cavity is folded outward or inward according to the actual situation, and no further limitation is made here.

[0048] In some embodiments, the metal ring 1013 is a copper ring, and the metal ring 1013 can also be a stainless steel ring. Of course, the metal ring 1013 can also be a ring made of other metal materials, for example, an aluminum ring, a silver ring, etc.

[0049] In some embodiments, the insulating ring 1012 is a ceramic ring. In a specific embodiment, it can be seen from Figure 9 that the ceramic ring increases the capacitance, enabling the resonance point to act on 1.5 GHz.

[0050] In some embodiments, as Figure 10 shown, the present invention also provides a high-order mode damping cavity 10, and the high-order mode damping cavity 10 includes the narrowband filtering structure 101 as described above.

[0051] In some embodiments, the high-order mode damping cavity 10 further includes a second cavity 102. The second cavity 102 is a cylindrical cavity, and the two ends of the cylindrical cavity are respectively provided with the above-mentioned narrowband filtering structure 101. One end of the first cavity 1011 in the narrowband filtering structure 101 is connected to the second cavity 102, and the other end of the first cavity 1011 extends axially away from the second cavity 102. The annular chamber 1014 is coaxially arranged with the second cavity 102.

[0052] Specifically, the first cavity 1011 and the second cavity 102 can be made by an integral forming method. The annular coupling groove 1015 on the first cavity 1011 is the coupling groove of the high-order mode damping cavity 10.

[0053] Specifically, when the first cavity 1011 is arranged, it can be arranged as a cylindrical cavity. A circular annular chamber 1014 penetrating the upper surface and the lower surface of the cylindrical cavity is opened on the cylindrical cavity. The circular annular chamber 1014 is the annular chamber 1014. An annular coupling groove is opened on the inner surface of the circular annular chamber 1014, and the annular coupling groove is coaxially arranged with the circular annular chamber 1014. Among them, the circular annular chamber 1014 can be integrally formed with the annular coupling groove 1015, that is, during the process of machining the circular annular chamber 1014, the annular coupling groove 1015 is formed on the inner surface of the circular annular chamber 1014.

[0054] Further, when the annular chamber 1014 is a circular annular chamber 1014, the metal ring 1013 is arranged as a circular ring, and the circular ring is coaxially arranged with the annular coupling groove. Correspondingly, the insulating ring 1012 is also arranged as a circular ring, and when the metal ring 1013 is sleeved on the insulating ring 1012, the insulating ring 1012 and the metal ring 1013 are coaxially arranged, that is to say, the insulating ring 1012 is also coaxially arranged with the annular coupling groove.

[0055] In this embodiment, as Figure 8 shown, the narrowband filtering structure 101 on the high-order mode damping cavity 10 is an RLC equivalent circuit structure, which can achieve narrowband filtering, that is, other resonance modes except the TM020 mode can pass through the coupling groove of the high-order mode damping cavity 10 to the damper 105 on the high-order mode damping cavity 10 without hindrance, while the TM020 mode cannot be transmitted. The RLC equivalent circuit structure reduces the magnetic field change rate near the wave node, reduces the sensitivity of the electromagnetic field leakage rate to the coupling groove position and the wave node position of the high-order mode damping cavity 10, and reduces the loss of the high-order mode damping cavity 10 to the working mode to less than 1%. The high-frequency parameters of the 1500 GHz - TM020 mode high-order mode damping cavity 10 are listed in Table 1.

[0056] Table 1

[0057] Freq. [MHz] Q0 R / Q [Ω] Ra [MΩ] Pm / Pc [%] 1500 <![CDATA[3.56×10 4 > 55.6 1.98 0.32

[0058] In some embodiments, a coupler 103, a plurality of symmetrically distributed tuners 104, a damper 105, a plurality of signal extraction ports 106, and a vacuum pumping port 107 are provided on the side wall of the second cavity 102; a damper 105 for absorbing waves is provided at the other end of each first cavity 1011.

[0059] Specifically, three tuners 104 can be provided, and the three tuners 104 are evenly distributed on the side wall of the second cavity 102, that is, the distance between any two adjacent tuners 104 is equal.

[0060] Two signal extraction ports 106 can be provided, and the two signal extraction ports 106 are symmetrically arranged, wherein each signal extraction port 106 is arranged between two tuners 104.

[0061] One vacuum pumping port 107 can be provided. Specifically, when setting, the vacuum pumping port 107 can be set between the tuner 104 and the signal extraction port 106.

[0062] One coupler 103 can be provided. Specifically, when setting, the coupler 103 is arranged between two tuners 104 and is separated from the signal extraction port 106 by a tuner 104.

[0063] When the damper 105 is set, one end of the first cavity 1011 can be folded back circumferentially. When folding back, one end of the first cavity 1011 can be folded outwards circumferentially or folded inwards circumferentially °, so that one end of the first cavity 1011 has an end - cover - shaped design. Among them, when folding back, it can be folded back by 90°; of course, one end of the first cavity 1011 can also be folded back at other angles, for example, 88°, 85°, 70°, 65°, 60°, 55°, etc. Those skilled in the art can determine the folding - back angle according to the actual situation and will not be overly limited here. The damper 105 is arranged on the end face formed after the other end of the first cavity 1011 is folded back. Among them, in the damper 105, wave absorption is carried out through the damper 105. Among them, when bending one end of the first cavity 1011 far from the second cavity 102, any one of the first cavities 1011 far from the second cavity 102 on the second cavity 102 can be folded back, or both ends of the two first cavities 1011 far from the second cavity 102 can be folded back. Those skilled in the art can determine the number of the first cavities 1011 that need to be folded back according to the actual situation.

[0064] In this embodiment, the first cavity 1011 is folded back to form an end - cover - shaped design, which facilitates the installation of the damper 105.

[0065] In some embodiments, the damper 105 can be a ferrite wave - absorbing material or a silicon carbide wave - absorbing material.

[0066] Here, it should be pointed out that the description of the above - mentioned embodiments of the high - order mode damping cavity 10 is similar to the description of the embodiments of the above - mentioned narrow - band filtering structure 101 and has similar beneficial effects to those of the above - mentioned high - order mode damping cavity 10. For the technical details not disclosed in the embodiments of the high - order mode damping cavity 10, please refer to the description of the embodiments of the narrow - band filtering structure 101 of the present invention for understanding.

[0067] In summary, the present invention provides a narrow - band filtering structure 101 and a high - order mode damping cavity 10, having the following beneficial effects:

[0068] Since the narrow - band filtering structure 101 is equivalent to an RLC equivalent circuit structure, the rate of change of the magnetic field near the wave node is reduced, the electromagnetic field leakage in the working mode is effectively reduced, and further the stability of the high - order mode damping cavity 10 working at a high gradient is improved.

[0069] It can be understood that the above embodiments only represent the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation to the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. A narrowband filtering structure, characterized in that: include: A first cavity, wherein the first cavity is provided with an annular cavity penetrating two opposite surfaces of the first cavity, and an inner surface of the annular cavity is provided with an annular coupling groove coaxially arranged with the annular cavity; An insulating ring, coaxially arranged with the annular coupling groove; The metal ring is sleeved on the insulating ring and is coaxial with the insulating ring. The metal ring is arranged in the annular coupling groove to form an RLC equivalent circuit structure.

2. The narrowband filtering structure according to claim 1, characterized in that: One end of the cavity is folded back in the circumferential direction.

3. The narrowband filtering structure according to claim 2, characterized in that: One end of the cavity is folded outward along the circumferential direction; or, one end of the cavity is folded inward along the circumferential direction.

4. The narrowband filtering structure according to any one of claims 1 to 3, characterized in that: The first cavity is a cylindrical cavity, and a circular ring-shaped cavity penetrating the upper surface and the lower surface of the first cavity is opened on the first cavity, and the circular ring-shaped cavity is the annular cavity.

5. The narrowband filtering structure according to claim 4, characterized in that: The metal ring is a circular ring, and the insulating ring is a circular ring.

6. The narrowband filtering structure according to claim 5, characterized in that: The metal ring is a copper ring or a stainless steel ring.

7. The narrowband filtering structure according to claim 5, characterized in that: The insulating ring is a ceramic ring.

8. A high-order mode damping cavity, characterized in that: include: A narrowband filtering structure as claimed in any one of claims 1 to 7.

9. The high-order mode damping cavity according to claim 8, characterized in that: The high-order mode damping cavity further comprises: The second cavity is a cylindrical cavity, and the narrowband filtering structure is respectively arranged at both ends of the second cavity. One end of the first cavity is connected to the second cavity, and the other end of the first cavity extends axially away from the second cavity. The annular chamber is coaxially arranged with the second cavity.

10. The high-order mode damping cavity according to claim 9, characterized in that: A coupler, a plurality of symmetrically distributed tuners, a damper, a plurality of signal extraction ports and a vacuum port are arranged on the side wall of the second cavity; a damper for wave absorption is arranged at the other end of each of the first cavities.

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